Fluidized Bed Urea Granulation Seed Generation
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Solution Overview
Problem
Existing processes for producing granular urea products in a fluidized-bed state face issues with non-uniform seed material size and shape, the need for recirculating final product as seeds, and high costs due to large, expensive equipment and the requirement for high-purity urea melt.
Innovation Solution
A novel process where small droplets of urea melt are solidified by a cooling medium to form starting particles, which then grow by contact with larger droplets, eliminating the need for external seed material and allowing granulation to proceed within the fluidized bed, using controlled air flow to maintain fluidization and particle size increments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If solid particles are produced externally in a separate equipment by solidification of urea melt, then uniform size and composition of seed material is achieved, but large and expensive equipment and additional evaporator are required
Solution Approach 1:
The system generates its own seed particles internally within the fluidized bed using the urea melt itself, eliminating the need for external seed generation equipment. The urea melt is sprayed onto the fluidized bed where it solidifies to form new seed particles in situ, making the system self-sufficient and removing dependency on separate seed production equipment.
Solution Approach 2:
The invention extracts and eliminates the separate seed generation equipment and evaporator from the overall system. By implementing internal seed generation within the fluidized bed, the complex external equipment required for seed production is removed, simplifying the process while maintaining seed uniformity.
2Productivity
If solid particles are screened and recirculated as seeds, then seed material is continuously available, but non-uniform size and shape of seed material results and additives concentration deviates
Solution Approach 1:
The system continuously generates fresh seed particles internally by spraying urea melt onto the fluidized bed, where the melt solidifies to form new seeds. This self-service mechanism ensures continuous availability of uniform seeds without relying on screening and recirculation of existing granules, thereby maintaining both productivity and seed uniformity.
Solution Approach 2:
The invention changes the state and properties of the seed material by generating seeds directly from liquid urea melt that solidifies in situ. This parameter change from recirculating solid granules to generating fresh solidified droplets ensures uniform size and composition while maintaining continuous seed supply for the granulation process.
3Manufacturing precision
If high-purity urea melt (>99.8%) is used for seed generation, then uniform composition is achieved, but additional evaporator and operational costs increase
Solution Approach 1:
The system uses the urea melt directly from the granulation process itself to generate seeds, without requiring external purification equipment. The melt that would otherwise be waste or require expensive evaporation is instead utilized in situ for seed generation, eliminating the need for additional evaporators and reducing energy costs while maintaining composition uniformity.
Solution Approach 2:
Instead of discarding or expensively purifying the urea melt through evaporation, the invention recovers and reuses it internally within the fluidized bed for seed generation. This recovery approach eliminates the need for additional evaporator equipment and operational costs while ensuring uniform seed composition from the process's own materials.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This process produces almost perfectly spherical granules with uniform composition, reducing equipment costs and operational expenses, as it operates with lower urea melt purity and eliminates the need for large seed generators and evaporators.
Implementation Method 1
small droplets of the urea melt being solidified by contact with a cooling medium, to form small solid particles
Implementation Method 2
the liquid droplet form a thin liquid layer around the solid particle, or at least a portion thereof, and said layer undergoes evaporation and solidification
Implementation Method 3
granules maintained in a fluidized-bed state
Data Source
AI summary
A process for production of a granular urea product in a fluidized-bed where: small droplets (10) of fresh urea melt are contacted with a cooling medium to form solid particles, said solid particles (11) are contacted with droplets of urea melt (12) which are larger than said germ particles, the solid particles and said droplets forming together larger solid particles (13), and said solid particles further increasing their size step by step and upon contact with droplets of urea melt, until the solid particles reaches a given size, and said solid particles are then subject to a further growing process by contact with liquid droplets now smaller than the solid particles, until a desired size of the granular product is reached.